Merge pull request #48 from zopefoundation/fix-46

Use dictionary lookups for testing subscribed status.

4 files changed, 276 insertions, 75 deletions

diff --git a/.coveragerc b/.coveragerc
index 58d9a3a..507ddc7 100644
--- a/.coveragerc
+++ b/.coveragerc
@@ -1,4 +1,4 @@
 [report]
 exclude_lines =
-    # pragma: no cover
+    pragma: no cover
     class I[A-Z]\w+\((Interface|I[A-Z].*)\):
diff --git a/CHANGES.rst b/CHANGES.rst
index 191f2fe..643b5f4 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -12,6 +12,12 @@ Changes
 - Make ``setuptools`` a hard dependency of ``setup.py``.
   (https://github.com/zopefoundation/zope.interface/issues/13)
 
+- Change a linear algorithm (O(n)) in ``Components.registerUtility`` and
+  ``Components.unregisterUtility`` into a dictionary lookup (O(1)) for
+  hashable components. This substantially improves the time taken to
+  manipulate utilities in large registries at the cost of some
+  additional memory usage. (https://github.com/zopefoundation/zope.interface/issues/46)
+
 4.2.0 (2016-06-10)
 ------------------
 
diff --git a/src/zope/interface/registry.py b/src/zope/interface/registry.py
index 83fcea2..2e1b085 100644
--- a/src/zope/interface/registry.py
+++ b/src/zope/interface/registry.py
@@ -13,9 +13,12 @@
 ##############################################################################
 """Basic components support
 """
+from collections import defaultdict
+from weakref import WeakKeyDictionary
+
 try:
     from zope.event import notify
-except ImportError: #pragma NO COVER
+except ImportError: # pragma: no cover
     def notify(*arg, **kw): pass
 
 from zope.interface.interfaces import ISpecification
@@ -38,6 +41,129 @@ from zope.interface._compat import CLASS_TYPES
 from zope.interface._compat import STRING_TYPES
 
 
+class _UnhashableComponentCounter(object):
+    # defaultdict(int)-like object for unhashable components
+
+    def __init__(self, otherdict):
+        # [(component, count)]
+        self._data = [item for item in otherdict.items()]
+
+    def __getitem__(self, key):
+        for component, count in self._data:
+            if component == key:
+                return count
+        return 0
+
+    def __setitem__(self, component, count):
+        for i, data in enumerate(self._data):
+            if data[0] == component:
+                self._data[i] = component, count
+                return
+        self._data.append((component, count))
+
+    def __delitem__(self, component):
+        for i, data in enumerate(self._data):
+            if data[0] == component:
+                del self._data[i]
+                return
+        raise KeyError(component) # pragma: no cover
+
+
+class _UtilityRegistrations(object):
+
+    _regs_for_components = WeakKeyDictionary()
+
+    @classmethod
+    def for_components(cls, components):
+        # We manage these utility/subscription registrations as associated
+        # objects with a weakref to avoid making any changes to
+        # the pickle format
+        try:
+            regs = cls._regs_for_components[components]
+        except KeyError:
+            regs = None
+        else:
+            # In case the components have been re-initted, clear the cache
+            # (zope.component.testing does this between tests)
+            if (regs._utilities is not components.utilities
+                or regs._utility_registrations is not components._utility_registrations):
+                regs = None
+
+        if regs is None:
+            regs = cls(components.utilities, components._utility_registrations)
+            cls._regs_for_components[components] = regs
+
+        return regs
+
+    @classmethod
+    def clear_cache(cls):
+        cls._regs_for_components.clear()
+
+    def __init__(self, utilities, utility_registrations):
+        # {provided -> {component: count}}
+        self._cache = defaultdict(lambda: defaultdict(int))
+        self._utilities = utilities
+        self._utility_registrations = utility_registrations
+
+        self.__populate_cache()
+
+    def __populate_cache(self):
+        for ((p, _), data) in iter(self._utility_registrations.items()):
+            component = data[0]
+            self.__cache_utility(p, component)
+
+    def __cache_utility(self, provided, component):
+        try:
+            self._cache[provided][component] += 1
+        except TypeError:
+            # The component is not hashable, and we have a dict. Switch to a strategy
+            # that doesn't use hashing.
+            prov = self._cache[provided] = _UnhashableComponentCounter(self._cache[provided])
+            prov[component] += 1
+
+    def __uncache_utility(self, provided, component):
+        provided = self._cache[provided]
+        # It seems like this line could raise a TypeError if component isn't
+        # hashable and we haven't yet switched to _UnhashableComponentCounter. However,
+        # we can't actually get in that situation. In order to get here, we would
+        # have had to cache the utility already which would have switched
+        # the datastructure if needed.
+        count = provided[component]
+        count -= 1
+        if count == 0:
+            del provided[component]
+        else:
+            provided[component] = count
+        return count > 0
+
+    def _is_utility_subscribed(self, provided, component):
+        try:
+            return self._cache[provided][component] > 0
+        except TypeError:
+            # Not hashable and we're still using a dict
+            return False
+
+    def registerUtility(self, provided, name, component, info, factory):
+        subscribed = self._is_utility_subscribed(provided, component)
+
+        self._utility_registrations[(provided, name)] = component, info, factory
+        self._utilities.register((), provided, name, component)
+
+        if not subscribed:
+            self._utilities.subscribe((), provided, component)
+
+        self.__cache_utility(provided, component)
+
+    def unregisterUtility(self, provided, name, component):
+        del self._utility_registrations[(provided, name)]
+        self._utilities.unregister((), provided, name)
+
+        subscribed = self.__uncache_utility(provided, component)
+
+        if not subscribed:
+            self._utilities.unsubscribe((), provided, component)
+
+
 @implementer(IComponents)
 class Components(object):
 
@@ -98,17 +224,7 @@ class Components(object):
                 return
             self.unregisterUtility(reg[0], provided, name)
 
-        subscribed = False
-        for ((p, _), data) in iter(self._utility_registrations.items()):
-            if p == provided and data[0] == component:
-                subscribed = True
-                break
-
-        self._utility_registrations[(provided, name)] = component, info, factory
-        self.utilities.register((), provided, name, component)
-
-        if not subscribed:
-            self.utilities.subscribe((), provided, component)
+        _UtilityRegistrations.for_components(self).registerUtility(provided, name, component, info, factory)
 
         if event:
             notify(Registered(
@@ -138,18 +254,7 @@ class Components(object):
             component = old[0]
 
         # Note that component is now the old thing registered
-
-        del self._utility_registrations[(provided, name)]
-        self.utilities.unregister((), provided, name)
-
-        subscribed = False
-        for ((p, _), data) in iter(self._utility_registrations.items()):
-            if p == provided and data[0] == component:
-                subscribed = True
-                break
-
-        if not subscribed:
-            self.utilities.unsubscribe((), provided, component)
+        _UtilityRegistrations.for_components(self).unregisterUtility(provided, name, component)
 
         notify(Unregistered(
             UtilityRegistration(self, provided, name, component, *old[1:])
diff --git a/src/zope/interface/tests/test_registry.py b/src/zope/interface/tests/test_registry.py
index 571bab3..c2a940a 100644
--- a/src/zope/interface/tests/test_registry.py
+++ b/src/zope/interface/tests/test_registry.py
@@ -73,7 +73,7 @@ class ComponentsTests(unittest.TestCase):
 
     def test_registerUtility_with_component_name(self):
         from zope.interface.declarations import named, InterfaceClass
-        
+
 
         class IFoo(InterfaceClass):
             pass
@@ -103,7 +103,7 @@ class ComponentsTests(unittest.TestCase):
         from zope.interface.declarations import InterfaceClass
         from zope.interface.interfaces import Registered
         from zope.interface.registry import UtilityRegistration
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -135,7 +135,7 @@ class ComponentsTests(unittest.TestCase):
         from zope.interface.declarations import InterfaceClass
         from zope.interface.interfaces import Registered
         from zope.interface.registry import UtilityRegistration
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -163,7 +163,7 @@ class ComponentsTests(unittest.TestCase):
 
     def test_registerUtility_no_provided_available(self):
         from zope.interface.declarations import InterfaceClass
-        
+
         class IFoo(InterfaceClass):
             pass
         class Foo(object):
@@ -181,7 +181,7 @@ class ComponentsTests(unittest.TestCase):
         from zope.interface.declarations import InterfaceClass
         from zope.interface.interfaces import Registered
         from zope.interface.registry import UtilityRegistration
-        
+
         class IFoo(InterfaceClass):
             pass
         class Foo(object):
@@ -210,7 +210,7 @@ class ComponentsTests(unittest.TestCase):
 
     def test_registerUtility_duplicates_existing_reg(self):
         from zope.interface.declarations import InterfaceClass
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -226,7 +226,7 @@ class ComponentsTests(unittest.TestCase):
 
     def test_registerUtility_w_different_info(self):
         from zope.interface.declarations import InterfaceClass
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -247,7 +247,7 @@ class ComponentsTests(unittest.TestCase):
 
     def test_registerUtility_w_different_names_same_component(self):
         from zope.interface.declarations import InterfaceClass
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -274,7 +274,7 @@ class ComponentsTests(unittest.TestCase):
         from zope.interface.interfaces import Unregistered
         from zope.interface.interfaces import Registered
         from zope.interface.registry import UtilityRegistration
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -312,7 +312,7 @@ class ComponentsTests(unittest.TestCase):
 
     def test_registerUtility_w_existing_subscr(self):
         from zope.interface.declarations import InterfaceClass
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -329,7 +329,7 @@ class ComponentsTests(unittest.TestCase):
 
     def test_registerUtility_wo_event(self):
         from zope.interface.declarations import InterfaceClass
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -357,7 +357,7 @@ class ComponentsTests(unittest.TestCase):
 
     def test_unregisterUtility_w_component_miss(self):
         from zope.interface.declarations import InterfaceClass
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -374,7 +374,7 @@ class ComponentsTests(unittest.TestCase):
         from zope.interface.declarations import InterfaceClass
         from zope.interface.interfaces import Unregistered
         from zope.interface.registry import UtilityRegistration
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -405,7 +405,7 @@ class ComponentsTests(unittest.TestCase):
         from zope.interface.declarations import InterfaceClass
         from zope.interface.interfaces import Unregistered
         from zope.interface.registry import UtilityRegistration
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -437,7 +437,7 @@ class ComponentsTests(unittest.TestCase):
         from zope.interface.declarations import InterfaceClass
         from zope.interface.interfaces import Unregistered
         from zope.interface.registry import UtilityRegistration
-        
+
         class IFoo(InterfaceClass):
             pass
         class Foo(object):
@@ -471,7 +471,7 @@ class ComponentsTests(unittest.TestCase):
         from zope.interface.declarations import InterfaceClass
         from zope.interface.interfaces import Unregistered
         from zope.interface.registry import UtilityRegistration
-        
+
         class IFoo(InterfaceClass):
             pass
         class Foo(object):
@@ -503,7 +503,7 @@ class ComponentsTests(unittest.TestCase):
 
     def test_unregisterUtility_w_existing_subscr(self):
         from zope.interface.declarations import InterfaceClass
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -519,9 +519,77 @@ class ComponentsTests(unittest.TestCase):
             comp.unregisterUtility(_to_reg, ifoo, _name2)
         self.assertEqual(comp.utilities._subscribers[0][ifoo][''], (_to_reg,))
 
+    def test_unregisterUtility_w_existing_subscr_non_hashable(self):
+        from zope.interface.declarations import InterfaceClass
+
+        class IFoo(InterfaceClass):
+            pass
+        ifoo = IFoo('IFoo')
+        _info = u'info'
+        _name1 = u'name1'
+        _name2 = u'name2'
+        _to_reg = dict()
+        comp = self._makeOne()
+        comp.registerUtility(_to_reg, ifoo, _name1, _info)
+        comp.registerUtility(_to_reg, ifoo, _name2, _info)
+        _monkey, _events = self._wrapEvents()
+        with _monkey:
+            comp.unregisterUtility(_to_reg, ifoo, _name2)
+        self.assertEqual(comp.utilities._subscribers[0][ifoo][''], (_to_reg,))
+
+    def test_unregisterUtility_w_existing_subscr_non_hashable_fresh_cache(self):
+        # We correctly populate the cache of registrations if it has gone away
+        # (for example, the Components was unpickled)
+        from zope.interface.declarations import InterfaceClass
+        from zope.interface.registry import _UtilityRegistrations
+
+        class IFoo(InterfaceClass):
+            pass
+        ifoo = IFoo('IFoo')
+        _info = u'info'
+        _name1 = u'name1'
+        _name2 = u'name2'
+        _to_reg = dict()
+        comp = self._makeOne()
+        comp.registerUtility(_to_reg, ifoo, _name1, _info)
+        comp.registerUtility(_to_reg, ifoo, _name2, _info)
+
+        _UtilityRegistrations.clear_cache()
+
+        _monkey, _events = self._wrapEvents()
+        with _monkey:
+            comp.unregisterUtility(_to_reg, ifoo, _name2)
+        self.assertEqual(comp.utilities._subscribers[0][ifoo][''], (_to_reg,))
+
+    def test_unregisterUtility_w_existing_subscr_non_hashable_reinitted(self):
+        # We correctly populate the cache of registrations if the base objects change
+        # out from under us
+        from zope.interface.declarations import InterfaceClass
+
+        class IFoo(InterfaceClass):
+            pass
+        ifoo = IFoo('IFoo')
+        _info = u'info'
+        _name1 = u'name1'
+        _name2 = u'name2'
+        _to_reg = dict()
+        comp = self._makeOne()
+        comp.registerUtility(_to_reg, ifoo, _name1, _info)
+        comp.registerUtility(_to_reg, ifoo, _name2, _info)
+
+        # zope.component.testing does this
+        comp.__init__('base')
+        comp.registerUtility(_to_reg, ifoo, _name2, _info)
+
+        _monkey, _events = self._wrapEvents()
+        with _monkey:
+            # Nothing to do, but we don't break either
+            comp.unregisterUtility(_to_reg, ifoo, _name2)
+        self.assertEqual(0, len(comp.utilities._subscribers))
+
     def test_unregisterUtility_w_existing_subscr_other_component(self):
         from zope.interface.declarations import InterfaceClass
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -539,13 +607,35 @@ class ComponentsTests(unittest.TestCase):
         self.assertEqual(comp.utilities._subscribers[0][ifoo][''],
                          (_other_reg,))
 
+    def test_unregisterUtility_w_existing_subscr_other_component_mixed_hash(self):
+        from zope.interface.declarations import InterfaceClass
+
+        class IFoo(InterfaceClass):
+            pass
+        ifoo = IFoo('IFoo')
+        _info = u'info'
+        _name1 = u'name1'
+        _name2 = u'name2'
+        # First register something hashable
+        _other_reg = object()
+        # Then it transfers to something unhashable
+        _to_reg = dict()
+        comp = self._makeOne()
+        comp.registerUtility(_other_reg, ifoo, _name1, _info)
+        comp.registerUtility(_to_reg, ifoo, _name2, _info)
+        _monkey, _events = self._wrapEvents()
+        with _monkey:
+            comp.unregisterUtility(_to_reg, ifoo, _name2)
+        self.assertEqual(comp.utilities._subscribers[0][ifoo][''],
+                         (_other_reg,))
+
     def test_registeredUtilities_empty(self):
         comp = self._makeOne()
         self.assertEqual(list(comp.registeredUtilities()), [])
 
     def test_registeredUtilities_notempty(self):
         from zope.interface.declarations import InterfaceClass
-        
+
         from zope.interface.registry import UtilityRegistration
         class IFoo(InterfaceClass):
             pass
@@ -630,7 +720,7 @@ class ComponentsTests(unittest.TestCase):
 
     def test_getUtilitiesFor_hit(self):
         from zope.interface.declarations import InterfaceClass
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -653,7 +743,7 @@ class ComponentsTests(unittest.TestCase):
 
     def test_getAllUtilitiesRegisteredFor_hit(self):
         from zope.interface.declarations import InterfaceClass
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -668,7 +758,7 @@ class ComponentsTests(unittest.TestCase):
 
     def test_registerAdapter_with_component_name(self):
         from zope.interface.declarations import named, InterfaceClass
-        
+
 
         class IFoo(InterfaceClass):
             pass
@@ -691,7 +781,7 @@ class ComponentsTests(unittest.TestCase):
         from zope.interface.declarations import InterfaceClass
         from zope.interface.interfaces import Registered
         from zope.interface.registry import AdapterRegistration
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -724,7 +814,7 @@ class ComponentsTests(unittest.TestCase):
 
     def test_registerAdapter_no_provided_available(self):
         from zope.interface.declarations import InterfaceClass
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -744,7 +834,7 @@ class ComponentsTests(unittest.TestCase):
         from zope.interface.declarations import implementer
         from zope.interface.interfaces import Registered
         from zope.interface.registry import AdapterRegistration
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -779,7 +869,7 @@ class ComponentsTests(unittest.TestCase):
 
     def test_registerAdapter_no_required_available(self):
         from zope.interface.declarations import InterfaceClass
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -795,7 +885,7 @@ class ComponentsTests(unittest.TestCase):
 
     def test_registerAdapter_w_invalid_required(self):
         from zope.interface.declarations import InterfaceClass
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -814,7 +904,7 @@ class ComponentsTests(unittest.TestCase):
         from zope.interface.interface import Interface
         from zope.interface.interfaces import Registered
         from zope.interface.registry import AdapterRegistration
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -851,7 +941,7 @@ class ComponentsTests(unittest.TestCase):
         from zope.interface.declarations import implementedBy
         from zope.interface.interfaces import Registered
         from zope.interface.registry import AdapterRegistration
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -889,7 +979,7 @@ class ComponentsTests(unittest.TestCase):
 
     def test_registerAdapter_w_required_containing_junk(self):
         from zope.interface.declarations import InterfaceClass
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -907,7 +997,7 @@ class ComponentsTests(unittest.TestCase):
         from zope.interface.declarations import InterfaceClass
         from zope.interface.interfaces import Registered
         from zope.interface.registry import AdapterRegistration
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -942,7 +1032,7 @@ class ComponentsTests(unittest.TestCase):
 
     def test_registerAdapter_wo_event(self):
         from zope.interface.declarations import InterfaceClass
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -1089,7 +1179,7 @@ class ComponentsTests(unittest.TestCase):
 
     def test_registeredAdapters_notempty(self):
         from zope.interface.declarations import InterfaceClass
-        
+
         from zope.interface.registry import AdapterRegistration
         class IFoo(InterfaceClass):
             pass
@@ -1359,7 +1449,7 @@ class ComponentsTests(unittest.TestCase):
     def test_getAdapters_non_empty(self):
         from zope.interface.declarations import InterfaceClass
         from zope.interface.declarations import implementer
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -1393,7 +1483,7 @@ class ComponentsTests(unittest.TestCase):
 
     def test_registerSubscriptionAdapter_w_nonblank_name(self):
         from zope.interface.declarations import InterfaceClass
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -1411,7 +1501,7 @@ class ComponentsTests(unittest.TestCase):
         from zope.interface.declarations import InterfaceClass
         from zope.interface.interfaces import Registered
         from zope.interface.registry import SubscriptionRegistration
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -1449,7 +1539,7 @@ class ComponentsTests(unittest.TestCase):
         from zope.interface.declarations import implementer
         from zope.interface.interfaces import Registered
         from zope.interface.registry import SubscriptionRegistration
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -1487,7 +1577,7 @@ class ComponentsTests(unittest.TestCase):
         from zope.interface.declarations import InterfaceClass
         from zope.interface.interfaces import Registered
         from zope.interface.registry import SubscriptionRegistration
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -1523,7 +1613,7 @@ class ComponentsTests(unittest.TestCase):
 
     def test_registerSubscriptionAdapter_wo_event(self):
         from zope.interface.declarations import InterfaceClass
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -1546,7 +1636,7 @@ class ComponentsTests(unittest.TestCase):
 
     def test_registeredSubscriptionAdapters_notempty(self):
         from zope.interface.declarations import InterfaceClass
-        
+
         from zope.interface.registry import SubscriptionRegistration
         class IFoo(InterfaceClass):
             pass
@@ -1579,7 +1669,7 @@ class ComponentsTests(unittest.TestCase):
 
     def test_unregisterSubscriptionAdapter_w_nonblank_name(self):
         from zope.interface.declarations import InterfaceClass
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -1790,7 +1880,7 @@ class ComponentsTests(unittest.TestCase):
 
     def test_registerHandler_w_nonblank_name(self):
         from zope.interface.declarations import InterfaceClass
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -1805,7 +1895,7 @@ class ComponentsTests(unittest.TestCase):
         from zope.interface.declarations import InterfaceClass
         from zope.interface.interfaces import Registered
         from zope.interface.registry import HandlerRegistration
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -1837,7 +1927,7 @@ class ComponentsTests(unittest.TestCase):
 
     def test_registerHandler_wo_explicit_required_no_event(self):
         from zope.interface.declarations import InterfaceClass
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -1892,10 +1982,10 @@ class ComponentsTests(unittest.TestCase):
         self.assertEqual(subscribers[1].name, '')
         self.assertEqual(subscribers[1].factory, _factory2)
         self.assertEqual(subscribers[1].info, '')
- 
+
     def test_unregisterHandler_w_nonblank_name(self):
         from zope.interface.declarations import InterfaceClass
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -2055,7 +2145,7 @@ class UtilityRegistrationTests(unittest.TestCase):
 
     def _makeOne(self, component=None, factory=None):
         from zope.interface.declarations import InterfaceClass
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -2240,7 +2330,7 @@ class AdapterRegistrationTests(unittest.TestCase):
 
     def _makeOne(self, component=None):
         from zope.interface.declarations import InterfaceClass
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -2449,7 +2539,7 @@ class SubscriptionRegistrationTests(unittest.TestCase):
 
     def _makeOne(self, component=None):
         from zope.interface.declarations import InterfaceClass
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')
@@ -2486,7 +2576,7 @@ class HandlerRegistrationTests(unittest.TestCase):
 
     def _makeOne(self, component=None):
         from zope.interface.declarations import InterfaceClass
-        
+
         class IFoo(InterfaceClass):
             pass
         ifoo = IFoo('IFoo')